US20060028063A1 - System and method for controlling a hydraulic system - Google Patents
System and method for controlling a hydraulic system Download PDFInfo
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- US20060028063A1 US20060028063A1 US11/246,598 US24659805A US2006028063A1 US 20060028063 A1 US20060028063 A1 US 20060028063A1 US 24659805 A US24659805 A US 24659805A US 2006028063 A1 US2006028063 A1 US 2006028063A1
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- Prior art keywords
- pressure
- valve
- brake
- orifice
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/24—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to vehicle inclination or change of direction, e.g. negotiating bends
- B60T8/241—Lateral vehicle inclination
- B60T8/243—Lateral vehicle inclination for roll-over protection
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T11/00—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant
- B60T11/10—Transmitting braking action from initiating means to ultimate brake actuator without power assistance or drive or where such assistance or drive is irrelevant transmitting by fluid means, e.g. hydraulic
- B60T11/28—Valves specially adapted therefor
- B60T11/30—Bleed valves for hydraulic brake systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/18—Safety devices; Monitoring
- B60T17/22—Devices for monitoring or checking brake systems; Signal devices
- B60T17/221—Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems
- B60T17/222—Procedure or apparatus for checking or keeping in a correct functioning condition of brake systems by filling or bleeding of hydraulic systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
- B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
- B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
- B60T8/50—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition having means for controlling the rate at which pressure is reapplied to or released from the brake
- B60T8/5018—Pressure reapplication using restrictions
- B60T8/5025—Pressure reapplication using restrictions in hydraulic brake systems
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/2496—Self-proportioning or correlating systems
- Y10T137/2559—Self-controlled branched flow systems
- Y10T137/2562—Dividing and recombining
Definitions
- the present invention relates generally to hydraulic systems, and more specifically, to a method and apparatus for hydraulic control in an automobile braking system.
- Hydraulic systems are currently used in a variety of control systems, such as automobile braking systems.
- a hydraulic pressure generator main cylinder
- main cylinder main cylinder
- RSC rollover stability control
- the brake unit also includes tire sensors and electronic switching circuits for detection and monitoring of the rotational behavior of the tires and for the generation of electric brake pressure control signals for use in slip and rollover control.
- valves having a switchable orifice size primarily to improve noise and vibration harshness (NVH).
- Orifice size or state is typically determined by the pressure difference across one of the valves, switching from a large state to a small state in response to a high pressure difference. Pressure activated valve switching has previously not been directly controllable.
- a hydraulic system in one aspect of the invention, includes a fluid line adapted to contain a fluid.
- a switchable valve is coupled to the fluid line and includes a small orifice and a large orifice.
- the switchable valve is adapted to switch to the small orifice in response to a high pressure difference across the valve.
- the switchable valve is further adapted to switch to the large orifice in response to a low pressure difference across the valve.
- a controller is adapted to bleed a portion of the fluid in response to an onset of a pressure build, whereby the valve opens with the large orifice, thereby generating a maximum build gradient.
- the method also includes opening the large orifice of the valve in response to the reduced pressure difference thereby preventing a high pressure difference across the valve and generating a maximum pressure gradient.
- the present system may be incorporated in a rollover stability control system (RSC).
- RSC rollover stability control system
- One advantage of the invention is that pressure on the upstream side of the valve at the beginning of an RSC pressure build, may be relieved which causes the orifice to have a large opening during the pressure build.
- FIG. 1 is a diagrammatic view of a hydraulic system in accordance with one embodiment of the present invention.
- FIG. 2 is a diagrammatic view of a vehicle system in accordance with another embodiment of the present invention.
- FIG. 3 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention.
- FIG. 4 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention.
- FIG. 5 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention.
- FIG. 6 is a logic flow diagram of a method for controlling a switchable hydraulic valve in accordance with another embodiment of the present invention.
- FIG. 7 is a logic flow diagram of a method for controlling a switchable hydraulic valve in accordance with another embodiment of the present invention.
- the present invention is preferably used to maximize hydraulic fluid pressure gradients in automobile braking systems.
- the present invention may also be used to maximize pressure gradients in various types of hydraulic systems.
- the present invention is particularly suited for dynamic control systems such as yaw control, rollover stability control (RSC) and the like.
- a hydraulic system 10 including a fluid line 12 containing a hydraulic fluid is illustrated.
- the fluid is brake fluid.
- the fluid line 12 includes a switchable valve 14 and a control valve 17 for the switchable valve 14 , both coupled thereto.
- the valve 14 includes a small orifice, 16 and a large orifice 18 .
- the system 10 further includes a controller 20 or brake controller.
- the system 10 also includes various typical hydraulic components of a brake system 21 , such as: a valve 40 receiving fluid through the orifice 14 , a master or main cylinder 24 , coupled to the fluid line 12 , and an actuator 26 for the main cylinder 24 .
- the switchable valve 14 switches to the small orifice 16 in response to fluid flow through the control valve 17 by compressing the valve spring 15 in response to a high pressure difference across the valve 14 and switches to the large orifice 18 in response to a low pressure difference across the valve 14 .
- the large orifice 18 has a larger cross-sectional opening area than the small orifice 16 . That is, the small orifice 16 has a smaller cross-sectional area than the large orifice 18 .
- the hydraulic system 10 further includes the controller 20 electrically coupled to the bleed mechanism 22 or a control valve 31 of the bleed mechanism 22 .
- the controller may be stand-alone or incorporated into a large control system such as a dynamic control system or rollover controller 23 , as is illustrated herein.
- the controller 20 is preferably microprocessor-based and includes logic for bleeding a portion of the fluid in response to an onset of a pressure build through signaling the bleed mechanism 22 in response to signals from, for example, rollover sensors 25 .
- the controller 20 controls the switchable valve 14 to open with the large orifice 18 , thereby controlling the switchable valve 14 and generating a maximum build gradient. Functions of the controller 20 will be discussed in detail later.
- the fluid line 12 is coupled to the main cylinder 24 , which activates in response to the actuator 26 (here embodied as a pedal), and sends increased fluid pressure to the switchable valve 14 .
- the main cylinder 24 may also provide an increase in pressure due to various dynamic control systems of the vehicle 32 wherein the system 10 may be housed.
- the system 30 also includes a main cylinder 24 , a brake pedal 26 , and third and optionally fourth bleed mechanisms 52 , 53 .
- the control system 30 includes the fluid line 12 coupled to the switchable valve 14 , the first brake bleed mechanism 22 , and the second brake bleed mechanism 40 .
- the control system 30 also includes the controller 20 for controlling the switchable valve 14 through signaling the bleed mechanisms or valves 22 , 40 .
- the controller 20 generates signals in response to braking signals from the brake pedal 26 received in the main cylinder 24 and from RSC events or other stability or vehicle control events sensed by the sensors 25 .
- the system 30 includes at least one typical automotive fluid line 12 .
- the fluid line 12 contains a hydraulic fluid and has bleed mechanisms or valves 22 , 40 for bleeding a portion of the fluid in response to deswitch signals, as will be discussed later.
- the fluid line includes the switchable valve 14 coupled thereto.
- the switchable valve 14 includes the small orifice 16 and the large orifice 18 described above.
- the switchable valve 14 switches to the small orifice 16 in response to a high pressure difference across the valve 14 and switches to the large orifice 18 in response to a low pressure difference across the valve 14 .
- the fluid line 12 also includes bleed mechanisms 22 , 40 coupled thereto.
- the first brake bleed mechanism 22 and the second brake bleed mechanism 40 are embodied as switchable valves or caliper actuators, however, any alternate brake bleed mechanism known in the art is also embodied herein.
- the switchable valve 14 is the actuator for a first wheel, wherein the first bleed mechanism 22 is the valve for the other wheel on the same brake circuit.
- a pressure request is made on the other wheel, which is not undergoing a Roll Stability Control (RSC) event, to open the bleed mechanism 22 that bleeds brake fluid from the upstream side of the switchable valve 14 .
- RSC Roll Stability Control
- the bleed mechanisms 22 , 40 are electrically coupled to the controller 20 either directly or through actuators.
- the controller 20 generates the deswitch signal or deswitch flag at a beginning of a pressure build signal thereby relieving pressure on an upstream side of the switchable valve, 14 whereby the switchable valve 14 switches to the large orifice 18 thereby allowing maximum fluid flow through the switchable valve 14 .
- the length of the controller deswitch signal is controlled by a controller pulse timer 33 .
- the pulse timer 33 is controlled such that the length of the pulse is sufficient to briefly relieve pressure from the upstream side of the valve 14 , but is short enough to prevent a significant decrease in pressure on the downstream side of the valve 14 .
- this parameter is set to approximately 14 ms.
- the controller 20 determines the nature of the control event, such as an RSC control event, through a plurality of vehicle dynamic signals from sensors 25 coupled thereto.
- the sensors 25 may include roll rate sensors, yaw rate sensors, pitch rate sensors, lateral acceleration sensors, longitudinal acceleration sensors, speed sensors, or any other vehicle dynamic sensors known in the art.
- the controller 20 may control a safety device. Depending on the desired sensitivity of the system 30 and various other factors, not all the sensors are used in a commercial embodiment.
- the safety device may control the hydraulic fluid flow in the fluid line 12 , an airbag or a steering actuator or braking actuator at one or more of the wheels of the vehicle 32 .
- the system 44 also includes a fluid line 45 containing a hydraulic fluid.
- the fluid line 45 includes a secondary valve port 51 , a switchable valve 46 , and a control valve 47 for the switchable valve 46 , all coupled to the fluid line 45 .
- the valve 46 includes a small orifice 48 and a large orifice 49 .
- the switchable valve 46 switches to the small orifice 48 in response to fluid flow through the control valve 47 by compressing the valve spring 50 in response to a high pressure difference across the valve 46 and switches to the large orifice 49 in response to a low pressure difference across the valve 46 .
- the secondary valve port 51 is activated by a controller to bleed off a portion of the fluid. The fluid then flows out the outlet portion of the fluid line 45 , which will typically lead into a caliper or braking mechanism.
- the system 54 includes a fluid line 56 containing a hydraulic fluid.
- the fluid line 56 includes a switchable valve 58 and a control valve 60 for the switchable valve 58 , both coupled thereto.
- the valve 58 includes a small orifice 61 and a large orifice 62 .
- a controller activates the control valve 60 and directly controls the switchable valve 58 through a control device 63 , such as a solenoid, coupled to the valve 58 .
- a control device 63 such as a solenoid
- fluid is not bled off; the controller merely selects the large or small orifice to generate a maximum pressure build by generating a valve control signal.
- the hydraulic system 66 includes a fluid line 67 containing a hydraulic fluid.
- the fluid line 67 includes a switchable valve 68 and a control valve 70 for the switchable valve 68 , both coupled thereto.
- the valve 68 includes a small orifice 72 and a large orifice 74 .
- This embodiment allows pressure based switching under normal operation, while overriding it during a RSC event to switch to the larger orifice 74 .
- the controller generates a valve control signal during an RSC event while allowing normal valve switching the rest of the time.
- the valve 68 could be directly controlled at all times.
- FIGS. 1, 2 , and 6 one example of a logic flow diagram 80 for controlling hydraulic fluid in the fluid line 12 from FIG. 2 is illustrated.
- Logic starts in inquiry block 82 where a check is made whether conditions require a deswitch pulse initiation. For a positive response, operation block 84 activates, and the deswitch pulse is initiated. This includes setting a deswitch flag and pulse timer 33 .
- inquiry block 86 a check is made as to whether the deswitch pulse is already occurring. For a positive response, in operation block 88 , the pulse timer 33 is decremented. Inquiry block 90 activates in response to a signal from operation blocks 84 , 88 or a negative response to inquiry block 86 .
- inquiry block 90 a check is made whether reset conditions exist for the system. For a positive response, in operation block 92 , the deswitch flag and the timer 33 are reset.
- Input variables to the following logic include: RQST_RSC_CTRL (RSC control signals), DRIVER_BRAKING_FLAG (flag set in response to driver braking), AYC_REQ_PRESSURE (required AYC pressure), BRAKE_PRESSR_ESTMT (brake pressure estimate), and PRESSURE_MAIN_CYLINDER (main cylinder pressure).
- Output variables include: deswitch, and ctr_Deswitch_PRESSURE (deswitch pressure control). Parameters include: MAX_PRESS_INHIBIT, MAX_DELTAP_FOR_MC, and Deswtitch_Loops (the number of deswitch loops)
- the deswitch pressure counter decrements until it reaches zero. This is illustrated by the following logic: else if (Deswitch[FR]) if(ctr_Deswitch_PRESSURE[FR]) ctr_Deswitch_PRESSURE[FR]--;
- the deswitch flag and counter are reset if driver braking occurs or if significant pressure increase is not requested, as is illustrated: if ( Deswitch [FR] &&(DRIVER_BRAKING_FLAG
- Conditions to initiate the deswitch pulse include: pressure build across the valve 14 is requested; pressure build is not keeping up with the request (i.e. in a pressure lag condition—orifice is likely switched to small state.); orifice deswitch through a bleed pulse is feasible (the pressure drop across valve 14 can be sufficiently reduced without impacting control.); the orifice deswitch pulse has not already been performed during the current pressure lag condition; or the orifice deswitch pulse is not currently being performed.
- Conditions to reset the deswitch flag and timer 33 include: the pressure build no longer lags the request or driver braking (the pulse is not utilized if significant pressure built by the brake pedal 26 apply.)
- the pressure lag condition is determined when the pressure estimate for the caliper or brake actuator 22 is lower than the pressure request by at least, for example, 5 bar.
- FIGS. 1, 2 , and 7 a logic flow diagram 100 of a method for controlling the hydraulic system 30 including a switchable valve 14 having a small orifice 16 and a large orifice 18 is illustrated.
- Logic starts in operation block 102 where a pressure build is sensed within the fluid line 12 at the switchable valve 14 .
- fluid is bled within the fluid line 12 through the bleed mechanism 22 upstream of the switchable valve 14 .
- the large valve orifice 18 is open in response to the reduced pressure difference at the onset of the pressure build across the switchable valve 14 .
- a method for controlling a hydraulic system 30 including a switchable valve 14 having a small orifice 16 and a large orifice 18 includes bleeding off a small amount of a fluid at an upstream side of the valve 14 thereby generating a reduced pressure difference at the beginning of a pressure build across the valve 14 .
- the method further includes opening the large orifice 18 of the valve 14 in response to the reduced pressure difference. This begins a high pressure difference across the valve 14 and generates a maximum pressure gradient.
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Abstract
Description
- The present invention claims priority to provisional application No. 202-1523 filed on Feb. 26, 2003.
- The present invention relates generally to hydraulic systems, and more specifically, to a method and apparatus for hydraulic control in an automobile braking system.
- For hydraulic systems, forces and velocities are transmitted and controlled by transmitting and controlling fluid pressure and flow in a closed system. Pressure in hydraulic systems is calculated through the equation p=F/A, where p is pressure (psi), F is force (pounds), and A is area (square inches).
- Hydraulic systems are currently used in a variety of control systems, such as automobile braking systems.
- In typical braking systems, a hydraulic pressure generator (main cylinder) generates a braking pressure through hydraulic fluid lines in response to depression of a brake pedal, thereby operating a braking device mounted on each tire.
- For hydraulic control systems, such as rollover stability control (RSC) using the aforementioned braking systems, fast rates of pressure buildup are desirable. For RSC systems, an RSC designated control wheel must have a high pressure build gradient.
- To control pressure, the brake unit also includes tire sensors and electronic switching circuits for detection and monitoring of the rotational behavior of the tires and for the generation of electric brake pressure control signals for use in slip and rollover control.
- Many hydraulic systems, such as the aforementioned, utilize valves having a switchable orifice size, primarily to improve noise and vibration harshness (NVH). Orifice size or state is typically determined by the pressure difference across one of the valves, switching from a large state to a small state in response to a high pressure difference. Pressure activated valve switching has previously not been directly controllable.
- It would therefore be desirable to provide a system and method for preventing an orifice from switching from a large state to a small state during large build requests. It would also be desirable to provide a maximum pressure gradient and to provide direct pressure activated valve switching. The present invention is directed to these ends.
- It is therefore an object of the invention to provide a system for controlling switchable hydraulic valves so that the hydraulic pressure or pressure buildup in such systems may desirably be controlled.
- In one aspect of the invention, a hydraulic system includes a fluid line adapted to contain a fluid. A switchable valve is coupled to the fluid line and includes a small orifice and a large orifice. The switchable valve is adapted to switch to the small orifice in response to a high pressure difference across the valve. The switchable valve is further adapted to switch to the large orifice in response to a low pressure difference across the valve. A controller is adapted to bleed a portion of the fluid in response to an onset of a pressure build, whereby the valve opens with the large orifice, thereby generating a maximum build gradient.
- In a further aspect of the invention, a method for controlling a hydraulic system including a valve having a small orifice and a large orifice includes bleeding off a small amount of a fluid at an upstream side of the valve thereby generating a reduced pressure difference at an onset of a pressure build across the valve. The method also includes opening the large orifice of the valve in response to the reduced pressure difference thereby preventing a high pressure difference across the valve and generating a maximum pressure gradient.
- Thus, the present system may be incorporated in a rollover stability control system (RSC). One advantage of the invention is that pressure on the upstream side of the valve at the beginning of an RSC pressure build, may be relieved which causes the orifice to have a large opening during the pressure build.
- Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment and when taken in conjunction with the attached drawings and appended claims.
-
FIG. 1 is a diagrammatic view of a hydraulic system in accordance with one embodiment of the present invention. -
FIG. 2 is a diagrammatic view of a vehicle system in accordance with another embodiment of the present invention. -
FIG. 3 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention. -
FIG. 4 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention. -
FIG. 5 is a diagrammatic view of a hydraulic system in accordance with another embodiment of the present invention. -
FIG. 6 is a logic flow diagram of a method for controlling a switchable hydraulic valve in accordance with another embodiment of the present invention. -
FIG. 7 is a logic flow diagram of a method for controlling a switchable hydraulic valve in accordance with another embodiment of the present invention. - The present invention is preferably used to maximize hydraulic fluid pressure gradients in automobile braking systems. The present invention, however, may also be used to maximize pressure gradients in various types of hydraulic systems. The present invention is particularly suited for dynamic control systems such as yaw control, rollover stability control (RSC) and the like.
- Referring to
FIG. 1 , ahydraulic system 10, including afluid line 12 containing a hydraulic fluid is illustrated. In the present example, the fluid is brake fluid. Thefluid line 12 includes aswitchable valve 14 and acontrol valve 17 for theswitchable valve 14, both coupled thereto. Thevalve 14 includes a small orifice, 16 and alarge orifice 18. - The
system 10 further includes acontroller 20 or brake controller. Thesystem 10 also includes various typical hydraulic components of abrake system 21, such as: avalve 40 receiving fluid through theorifice 14, a master ormain cylinder 24, coupled to thefluid line 12, and anactuator 26 for themain cylinder 24. - The
switchable valve 14 switches to thesmall orifice 16 in response to fluid flow through thecontrol valve 17 by compressing thevalve spring 15 in response to a high pressure difference across thevalve 14 and switches to thelarge orifice 18 in response to a low pressure difference across thevalve 14. Thelarge orifice 18 has a larger cross-sectional opening area than thesmall orifice 16. That is, thesmall orifice 16 has a smaller cross-sectional area than thelarge orifice 18. - The
hydraulic system 10 further includes thecontroller 20 electrically coupled to thebleed mechanism 22 or acontrol valve 31 of thebleed mechanism 22. The controller may be stand-alone or incorporated into a large control system such as a dynamic control system orrollover controller 23, as is illustrated herein. Thecontroller 20 is preferably microprocessor-based and includes logic for bleeding a portion of the fluid in response to an onset of a pressure build through signaling thebleed mechanism 22 in response to signals from, for example,rollover sensors 25. Thecontroller 20 controls theswitchable valve 14 to open with thelarge orifice 18, thereby controlling theswitchable valve 14 and generating a maximum build gradient. Functions of thecontroller 20 will be discussed in detail later. - The
fluid line 12 is coupled to themain cylinder 24, which activates in response to the actuator 26 (here embodied as a pedal), and sends increased fluid pressure to theswitchable valve 14. Themain cylinder 24 may also provide an increase in pressure due to various dynamic control systems of thevehicle 32 wherein thesystem 10 may be housed. - Referring to
FIG. 2 , acontrol system 30 for anautomotive vehicle 32 having afluid line 12 having aswitchable valve 14, a first brake bleed mechanism orvalve 22, a second brake bleed mechanism orvalve 40, rollover sensors 25 (sensor cluster), and abrake controller 20 within arollover controller 23, is illustrated. Thesystem 30 also includes amain cylinder 24, abrake pedal 26, and third and optionally fourthbleed mechanisms - The
control system 30 includes thefluid line 12 coupled to theswitchable valve 14, the firstbrake bleed mechanism 22, and the secondbrake bleed mechanism 40. Thecontrol system 30 also includes thecontroller 20 for controlling theswitchable valve 14 through signaling the bleed mechanisms orvalves controller 20 generates signals in response to braking signals from thebrake pedal 26 received in themain cylinder 24 and from RSC events or other stability or vehicle control events sensed by thesensors 25. - The
system 30 includes at least one typicalautomotive fluid line 12. Thefluid line 12 contains a hydraulic fluid and has bleed mechanisms orvalves - The fluid line includes the
switchable valve 14 coupled thereto. Theswitchable valve 14 includes thesmall orifice 16 and thelarge orifice 18 described above. Theswitchable valve 14 switches to thesmall orifice 16 in response to a high pressure difference across thevalve 14 and switches to thelarge orifice 18 in response to a low pressure difference across thevalve 14. - The
fluid line 12 also includes bleedmechanisms brake bleed mechanism 22 and the secondbrake bleed mechanism 40 are embodied as switchable valves or caliper actuators, however, any alternate brake bleed mechanism known in the art is also embodied herein. - In the present embodiment, the
switchable valve 14 is the actuator for a first wheel, wherein thefirst bleed mechanism 22 is the valve for the other wheel on the same brake circuit. A pressure request is made on the other wheel, which is not undergoing a Roll Stability Control (RSC) event, to open thebleed mechanism 22 that bleeds brake fluid from the upstream side of theswitchable valve 14. - The
bleed mechanisms controller 20 either directly or through actuators. Thecontroller 20 generates the deswitch signal or deswitch flag at a beginning of a pressure build signal thereby relieving pressure on an upstream side of the switchable valve, 14 whereby theswitchable valve 14 switches to thelarge orifice 18 thereby allowing maximum fluid flow through theswitchable valve 14. - The length of the controller deswitch signal is controlled by a
controller pulse timer 33. Thepulse timer 33 is controlled such that the length of the pulse is sufficient to briefly relieve pressure from the upstream side of thevalve 14, but is short enough to prevent a significant decrease in pressure on the downstream side of thevalve 14. In the present embodiment, this parameter is set to approximately 14 ms. - The
controller 20 determines the nature of the control event, such as an RSC control event, through a plurality of vehicle dynamic signals fromsensors 25 coupled thereto. Thesensors 25 may include roll rate sensors, yaw rate sensors, pitch rate sensors, lateral acceleration sensors, longitudinal acceleration sensors, speed sensors, or any other vehicle dynamic sensors known in the art. - Based upon inputs from the
sensors 25, thecontroller 20 may control a safety device. Depending on the desired sensitivity of thesystem 30 and various other factors, not all the sensors are used in a commercial embodiment. The safety device may control the hydraulic fluid flow in thefluid line 12, an airbag or a steering actuator or braking actuator at one or more of the wheels of thevehicle 32. - Referring to
FIG. 3 , an alternate embodiment of ahydraulic system 44, in accordance with another embodiment of the present invention, is illustrated. Thesystem 44 also includes afluid line 45 containing a hydraulic fluid. Thefluid line 45 includes asecondary valve port 51, aswitchable valve 46, and acontrol valve 47 for theswitchable valve 46, all coupled to thefluid line 45. Thevalve 46 includes asmall orifice 48 and alarge orifice 49. - The
switchable valve 46 switches to thesmall orifice 48 in response to fluid flow through thecontrol valve 47 by compressing thevalve spring 50 in response to a high pressure difference across thevalve 46 and switches to thelarge orifice 49 in response to a low pressure difference across thevalve 46. - In this embodiment, the
secondary valve port 51 is activated by a controller to bleed off a portion of the fluid. The fluid then flows out the outlet portion of thefluid line 45, which will typically lead into a caliper or braking mechanism. - Referring to
FIG. 4 , an alternate embodiment of ahydraulic system 54, in accordance with another embodiment of the present invention, is illustrated. Thesystem 54 includes afluid line 56 containing a hydraulic fluid. Thefluid line 56 includes aswitchable valve 58 and acontrol valve 60 for theswitchable valve 58, both coupled thereto. Thevalve 58 includes asmall orifice 61 and alarge orifice 62. - For this embodiment, a controller activates the
control valve 60 and directly controls theswitchable valve 58 through acontrol device 63, such as a solenoid, coupled to thevalve 58. In this embodiment, fluid is not bled off; the controller merely selects the large or small orifice to generate a maximum pressure build by generating a valve control signal. - Referring to
FIG. 5 , an alternate embodiment of ahydraulic system 66 is illustrated. Thehydraulic system 66 includes afluid line 67 containing a hydraulic fluid. Thefluid line 67 includes aswitchable valve 68 and acontrol valve 70 for theswitchable valve 68, both coupled thereto. Thevalve 68 includes asmall orifice 72 and alarge orifice 74. - This embodiment allows pressure based switching under normal operation, while overriding it during a RSC event to switch to the
larger orifice 74. In other words, the controller generates a valve control signal during an RSC event while allowing normal valve switching the rest of the time. Alternatively, thevalve 68 could be directly controlled at all times. - Referring to
FIGS. 1, 2 , and 6, one example of a logic flow diagram 80 for controlling hydraulic fluid in thefluid line 12 fromFIG. 2 is illustrated. - Logic starts in
inquiry block 82 where a check is made whether conditions require a deswitch pulse initiation. For a positive response,operation block 84 activates, and the deswitch pulse is initiated. This includes setting a deswitch flag andpulse timer 33. - Otherwise, in
inquiry block 86, a check is made as to whether the deswitch pulse is already occurring. For a positive response, inoperation block 88, thepulse timer 33 is decremented.Inquiry block 90 activates in response to a signal from operation blocks 84, 88 or a negative response toinquiry block 86. - In
inquiry block 90, a check is made whether reset conditions exist for the system. For a positive response, inoperation block 92, the deswitch flag and thetimer 33 are reset. - Otherwise, in response to operation block 92 or a negative response to
inquiry block 90, a check is made whether the pulse timer signal is greater than zero. For a positive response, in operation block 96, thebleed mechanism 22 is opened. Otherwise, in operation block 98, thebleed mechanism 22 is closed. The logic flow diagram then returns toinquiry block 82, and logic continues therefrom. - An example of logic for a
vehicle controller 30 in accordance withFIG. 6 is included herein below. - Input variables to the following logic include: RQST_RSC_CTRL (RSC control signals), DRIVER_BRAKING_FLAG (flag set in response to driver braking), AYC_REQ_PRESSURE (required AYC pressure), BRAKE_PRESSR_ESTMT (brake pressure estimate), and PRESSURE_MAIN_CYLINDER (main cylinder pressure).
- Output variables include: deswitch, and ctr_Deswitch_PRESSURE (deswitch pressure control). Parameters include: MAX_PRESS_INHIBIT, MAX_DELTAP_FOR_MC, and Deswtitch_Loops (the number of deswitch loops)
- The following section of logic determines if RSC pressure build at the front left requires deswitch pulse at the front right wheel:
if(RQST_RSC_CTRL[FL] &&!Deswitch[FR] &&!DRIVER_BRAKING_FLAG &&(AYC_REQ_PRESSURE[FL]>(BRAKE_PRESSR_ESTMT [FL]+MAX_PRESS_INHIBIT)) &&(PRESSURE_MAIN_CYLINDER<(MAX(BRAKE_PRESSR _ESTMT[FL], BRAKE_PRESSR_ESTMT[FR])+MAX_DELTAP_FOR_MC)) && ! ctr_Deswitch_PRESSURE[FL]) {Deswitch[FR]=TRUE; ctr_Deswitch_PRESSURE[FR]=Deswtitch_Loops;} - The criteria “&&!ctr_Deswitch_PRESSURE[FL]” below is used to prevent a deswitch pulse on the front left wheel from triggering a deswitch pulse on the front right wheel. This is required because the deswitch pressure request is reflected in the AYC_REQ_PRESSURE.
- If the deswitch flag has been set, the deswitch pressure counter (deswitch timer 33) decrements until it reaches zero. This is illustrated by the following logic:
else if (Deswitch[FR]) if(ctr_Deswitch_PRESSURE[FR]) ctr_Deswitch_PRESSURE[FR]--; - The deswitch flag and counter are reset if driver braking occurs or if significant pressure increase is not requested, as is illustrated:
if ( Deswitch [FR] &&(DRIVER_BRAKING_FLAG||(AYC_REQ_PRESSURE[F L]<(BRAKE_PRESSR_ESTMT[FL]+MIN_PRESS_INHIBI T)) {Deswitch[FR]=FALSE; ctr_Deswitch_PRESSURE[FR]=0;} - The same technique is used for RSC control on the front right wheel by interchanging the subscript values front right (FR) & front left (FL). Also, rear braking may be performed in a similar manner, alone or together with front braking.
- Conditions to initiate the deswitch pulse include: pressure build across the
valve 14 is requested; pressure build is not keeping up with the request (i.e. in a pressure lag condition—orifice is likely switched to small state.); orifice deswitch through a bleed pulse is feasible (the pressure drop acrossvalve 14 can be sufficiently reduced without impacting control.); the orifice deswitch pulse has not already been performed during the current pressure lag condition; or the orifice deswitch pulse is not currently being performed. - Conditions to reset the deswitch flag and
timer 33 include: the pressure build no longer lags the request or driver braking (the pulse is not utilized if significant pressure built by thebrake pedal 26 apply.) - In the present embodiment, the pressure lag condition is determined when the pressure estimate for the caliper or
brake actuator 22 is lower than the pressure request by at least, for example, 5 bar. - Referring to
FIGS. 1, 2 , and 7, a logic flow diagram 100 of a method for controlling thehydraulic system 30 including aswitchable valve 14 having asmall orifice 16 and alarge orifice 18 is illustrated. - Logic starts in
operation block 102 where a pressure build is sensed within thefluid line 12 at theswitchable valve 14. - In
operation block 104, fluid is bled within thefluid line 12 through thebleed mechanism 22 upstream of theswitchable valve 14. - In
operation block 106, thelarge valve orifice 18 is open in response to the reduced pressure difference at the onset of the pressure build across theswitchable valve 14. - In
operation block 108, the bleeding of the fluid upstream of theswitchable valve 14 is halted after fluid flow is continued through thelarge valve orifice 18. - In operation, a method for controlling a
hydraulic system 30 including aswitchable valve 14 having asmall orifice 16 and alarge orifice 18 includes bleeding off a small amount of a fluid at an upstream side of thevalve 14 thereby generating a reduced pressure difference at the beginning of a pressure build across thevalve 14. The method further includes opening thelarge orifice 18 of thevalve 14 in response to the reduced pressure difference. This begins a high pressure difference across thevalve 14 and generates a maximum pressure gradient. - While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.
Claims (21)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US11/246,598 US8444229B2 (en) | 2003-02-26 | 2005-10-07 | System and method for controlling a hydraulic system |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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US44996203P | 2003-02-26 | 2003-02-26 | |
US10/250,293 US6997524B2 (en) | 2003-02-26 | 2003-06-20 | System and method for controlling a hydraulic system |
US11/246,598 US8444229B2 (en) | 2003-02-26 | 2005-10-07 | System and method for controlling a hydraulic system |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
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US10/250,293 Division US6997524B2 (en) | 2003-02-26 | 2003-06-20 | System and method for controlling a hydraulic system |
US10/250,293 Continuation US6997524B2 (en) | 2003-02-26 | 2003-06-20 | System and method for controlling a hydraulic system |
Publications (2)
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US20060028063A1 true US20060028063A1 (en) | 2006-02-09 |
US8444229B2 US8444229B2 (en) | 2013-05-21 |
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US10/250,293 Expired - Fee Related US6997524B2 (en) | 2003-02-26 | 2003-06-20 | System and method for controlling a hydraulic system |
US11/246,598 Expired - Fee Related US8444229B2 (en) | 2003-02-26 | 2005-10-07 | System and method for controlling a hydraulic system |
Family Applications Before (1)
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US10/250,293 Expired - Fee Related US6997524B2 (en) | 2003-02-26 | 2003-06-20 | System and method for controlling a hydraulic system |
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US (2) | US6997524B2 (en) |
EP (1) | EP1452414B1 (en) |
DE (1) | DE602004023020D1 (en) |
Cited By (1)
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US20090075351A1 (en) * | 2007-03-16 | 2009-03-19 | Burk Mark J | Compositions and methods for the biosynthesis of 1,4-butanediol and its precursors |
Families Citing this family (1)
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DE102013204716B3 (en) | 2013-03-18 | 2014-05-28 | Ford Global Technologies, Llc | Method for operating a hydraulic brake system |
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US4294113A (en) * | 1980-02-04 | 1981-10-13 | Dresser Industries, Inc. | Anti-surge system for gases and other media |
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DK348877A (en) | 1977-08-04 | 1979-02-05 | M Rasmussen | SYSTEM FOR VENTILATION OF HYDRAULIC AUTOMOBILE BRAKES |
JPS6033158A (en) * | 1983-07-29 | 1985-02-20 | Toyota Motor Corp | Antiskid braking device for vehicle |
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JP2536909B2 (en) | 1988-09-30 | 1996-09-25 | アイシン精機株式会社 | Hydraulic brake device |
DE3940177C2 (en) * | 1989-12-05 | 1999-03-18 | Teves Gmbh Alfred | Slip-controlled hydraulic vehicle brake system |
US5137339A (en) | 1990-08-17 | 1992-08-11 | Allied-Signal Inc. | Regulator supply valve for adaptive braking and traction control systems |
GB2252140A (en) * | 1991-01-26 | 1992-07-29 | Lucas Ind Plc | Solenoid-operated fluid-flow control valve assemblies |
DE4128120A1 (en) * | 1991-08-24 | 1993-02-25 | Bosch Gmbh Robert | HYDRAULIC VEHICLE BRAKE SYSTEM WITH ANTI-BLOCKING DEVICE |
JP2882154B2 (en) | 1992-01-07 | 1999-04-12 | 日産自動車株式会社 | Traction control device for vehicles |
JPH06247272A (en) | 1993-02-25 | 1994-09-06 | Jidosha Kiki Co Ltd | Modulator for anti-skid brake control device |
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JP3715054B2 (en) | 1996-12-27 | 2005-11-09 | 日信工業株式会社 | Antilock brake control device for vehicle |
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EP1023212B1 (en) | 1997-10-17 | 2005-03-30 | Continental Teves AG & Co. oHG | Method for improving the control performance of a motor vehicle control system |
JPH11278234A (en) | 1998-03-31 | 1999-10-12 | Tokico Ltd | Brake force control device |
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JP4089062B2 (en) | 1999-01-28 | 2008-05-21 | アイシン精機株式会社 | Brake device |
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GB0016271D0 (en) | 2000-07-04 | 2000-08-23 | Meritor Automotive Inc | Vehicle braking systems |
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2003
- 2003-06-20 US US10/250,293 patent/US6997524B2/en not_active Expired - Fee Related
-
2004
- 2004-02-04 EP EP20040100403 patent/EP1452414B1/en not_active Expired - Fee Related
- 2004-02-04 DE DE200460023020 patent/DE602004023020D1/en not_active Expired - Lifetime
-
2005
- 2005-10-07 US US11/246,598 patent/US8444229B2/en not_active Expired - Fee Related
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US4294113A (en) * | 1980-02-04 | 1981-10-13 | Dresser Industries, Inc. | Anti-surge system for gases and other media |
Cited By (1)
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US20090075351A1 (en) * | 2007-03-16 | 2009-03-19 | Burk Mark J | Compositions and methods for the biosynthesis of 1,4-butanediol and its precursors |
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US8444229B2 (en) | 2013-05-21 |
US20040164609A1 (en) | 2004-08-26 |
EP1452414A1 (en) | 2004-09-01 |
EP1452414B1 (en) | 2009-09-09 |
DE602004023020D1 (en) | 2009-10-22 |
US6997524B2 (en) | 2006-02-14 |
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